1. Field of the Invention
Aspects of the present invention relate to a battery management system. More particularly, aspects of the present invention relates to a battery management system (“BMS”) that can be used in an electric vehicle using electrical energy, and a driving method thereof.
2. Description of the Related Art
A vehicle using an internal combustion engine using gasoline or diesel as a main fuel tends to create environmental pollution such as air pollution. Accordingly, in order to reduce pollution, great efforts have recently been made to develop electric vehicles and hybrid vehicles.
An electric vehicle is a vehicle that uses electrical energy from a battery pack, typically including a plurality of rechargeable battery cells that can be charged and discharged many times. Electric vehicles do not emit noxious exhaust gas and are almost noiseless since they are mainly powered by the battery pack.
A hybrid vehicle is a vehicle that is configured to operate with two or more kinds of power sources such as an internal combustion engine and a battery powered engine. Currently, hybrid vehicles are being developed that use an internal combustion engine and a fuel cell that directly obtains electrical energy by a chemical reaction between hydrogen and oxygen and that stores the electrical energy in a battery pack.
The number of rechargeable battery cells in an electric vehicle using a battery powered engine is currently increasing, and therefore, vehicles need a battery management system (BMS) to provide a cell balancing control method in order to effectively manage a plurality of battery cells connected to each other.
In particular, the state of charge (“SOC”) of a battery is determined by detecting an open circuit voltage (“OCV”) in a key-on state and an initial SOC is inferred using a table relating SOCs to OCVs based on temperature. However, since the conventional initial SOC inferring method is carried out without considering factors such as the amount of time that a battery was in a key-off state before the subsequent key-on time point, an OCV error range caused by temperature, and an OCV detected in the key-on state as well as a temperature and an OVC detected in the key-off state, but simply uses an OCV table relating SOCs and OVCs based on temperature, the conventional method may be inaccurate in inferring the precise initial SOC upon the start of the key-on state.
The above information disclosed in this Background section is provided for enhancement of understanding of the background of various aspects of the invention. The discussion of such information is not intended to represent or suggest that such information constitutes prior art that is already known in this country to a person of ordinary skill in the art.